Chapter XXI. Messages into Space
 

Tom Swift's announcement of the practical completion of his wireless plant brought hope to the discouraged hearts of the castaways. They crowded about him, and asked all manner of questions.

Mr. Fenwick and Mr. Damon came in for their share of attention, for Tom said had it not been for the aid of his friends he never could have accomplished what he did. Then they all trooped up to the little shack, and inspected the plant.

As the young inventor had said, it was necessarily crude, but when he set the gasolene motor going, and the dynamo whizzed and hummed, sending out great, violet-hued sparks, they were all convinced that the young inventor had accomplished wonders, considering the materials at his disposal.

"But it's going to be no easy task to rig up the sending and receiving wires," declared Tom. "That will take some time."

"Have you got the wire?" asked Mr. Jenks.

"I took it from the stays of the airship," was Tom's reply, and he recalled the day he was at that work, when the odd man had exhibited the handful of what he said were diamonds. Tom wondered if they really were, and he speculated as to what might be the secret of Phantom Mountain, to which Mr. Jenks had referred.

But now followed a busy time for all. Under the direction of the young inventor, they began to string the wires from the top of the dead tree, to a smaller one, some distance away, using five wires, set parallel, and attached to a wooden spreader, or stay. The wires were then run to the dynamo, and the receiving coil, and the necessary ground wires were installed.

"But I can't understand how you are going to do it," said Mrs. Nestor. "I've read about wireless messages, but I can't get it through my head. How is it done, Mr. Swift?"

"The theory is very simple," said the young inventor. "To send a message by wire, over a telegraph system, a battery or dynamo is used. This establishes a current over wires stretched between two points. By means of what is called a 'key' this current is interrupted, or broken, at certain intervals, making the sounding instrument send out clicks. A short click is called a dot, and a long click a dash. By combinations of dots, dashes, and spaces between the dots and dashes, letters are spelled out. For instance, a dot and a space and a dash, represent the letter 'A' and so on."

"I understand so far," admitted Mrs. Nestor.

"In telegraphing without wires," went on Tom, "the air is used in place of a metallic conductor, with the help of the earth, which in itself is a big magnet, or a battery, as you choose to regard it. The earth helps to establish the connection between places where there are no wires, when we 'ground' certain conductors."

"To send a wireless message a current is generated by a dynamo. The current flows along until it gets to the ends of the sending wires, which we have just strung. Then it leaps off into space, so to speak, until it reaches the receiving wires, wherever they may be erected. That is why any wireless receiving station, within a certain radius, can catch any messages that may be flying through the air--that is unless certain apparatus is tuned, or adjusted, to prevent this."

"Well, once the impulses, or electric currents, are sent out into space, all that is necessary to do is to break, or interrupt them at certain intervals, to make dots, dashes and spaces. These make corresponding clicks in the telephone receiver which the operator at the receiving station wears on his ear. He hears the code of clicks, and translates them into letters, the letters into words and the words into sentences. That is how wireless messages are sent."

"And do you propose to send some that way?" asked Mrs. Anderson.

"I do," replied Tom, with a smile.

"Where to?" Mrs. Nestor wanted to know.

"That's what I can't tell," was Tom's reply. "I will have to project them off into space, and trust to chance that some listening wireless operator will 'pick them up,' as they call it, and send us aid."

"But are wireless operators always listening?" asked Mr. Nestor.

"Somewhere, some of them are--I hope," was Tom's quiet answer. "As I said, we will have to trust much to chance. But other people have been saved by sending messages off into space; and why not we? Sinking steamers have had their passengers taken off when the operator called for help, merely by sending a message into space."

"But how can we tell them where to come for us--on this unknown island?" inquired Mrs. Anderson.

"I fancy Captain Mentor can supply our longitude and latitude," answered Tom. "I will give that with every message I send out, and help may come--some day."

"It can't come any too quick for me!" declared Mr. Damon. "Bless my door knob, but my wife must be worrying about my absence!"

"What message for help will you send?" Captain Mentor wanted to know.

"I am going to use the old call for aid," was the reply of the young inventor. "I shall flash into space the three letters 'C.Q.D.' They stand for 'Come Quick--Danger.' A new code call has been instituted for them, but I am going to rely on the old one, as, in this part of the world, the new one may not be so well understood. Then I will follow that by giving our position in the ocean, as nearly as Captain Mentor can figure it out. I will repeat this call at intervals until we get help--"

"Or until the island sinks," added the scientist, grimly.

"Here! Don't mention that any more," ordered Mr. Hosbrook. "It's getting on my nerves! We may be rescued before that awful calamity overtakes us."

"I don't believe so," was Mr. Parker's reply, and he actually seemed to derive pleasure from his gloomy prophecy.

"It's lucky you understand wireless telegraphy, Tom Swift," said Mr. Nestor admiringly, and the other joined in praising the young inventor, until, blushing, he hurried off to make some adjustments to his apparatus.

"Can you compute our longitude and latitude, Captain Mentor," asked the millionaire yacht owner.

"I think so," was the reply. "Not very accurately, of course, for all my papers and instruments went down in the Resolute. But near enough for the purpose, I fancy. I'll get right to work at it, and let Mr. Swift have it."

"I wish you would. The sooner we begin calling for help the better. I never expected to be in such a predicament as this, but it is wonderful how that young fellow worked out his plan of rescue. I hope he succeeds."

It took some little time for the commander to figure their position, and then it was only approximate. But at length he handed Tom a piece of paper with the latitude and longitude written on it.

In the meanwhile, the young inventor had been connecting up his apparatus. The wires were now all strung, and all that was necessary was to start the motor and dynamo.

A curious throng gathered about the little shack as Tom announced that he was about to flash into space the first message calling for help. He took his place at the box, to which had been fastened the apparatus for clicking off the Morse letters.

"Well, here we go," he said, with a smile.

His fingers clasped the rude key he had fashioned from bits of brass and hard rubber. The motor was buzzing away, and the electric dynamo was purring like some big cat.

Just as Tom opened the circuit, to send the current into the instrument, there came an omnious rumbling of the earth.

"Another quake!" screamed Mrs. Anderson. But it was over in a second, and calmness succeeded the incipient panic.

Suddenly, overhead, there sounded a queer crackling noise, a vicious, snapping, as if from some invisible whips.

"Mercy! What's that?" cried Mrs. Nestor.

"The wireless," replied Tom, quietly. "I am going to send a message for help, off into space. I hope some one receives it--and answers," he added, in a low tone.

The crackling increased. While they gathered about him, Tom Swift pressed the key, making and breaking the current until he had sent out from Earthquake Island the three letters--"C.Q.D." And he followed them by giving their latitude and longitude. Over and over again he flashed out this message.

Would it be answered? Would help come? If so, from where? And if so, would it be in time? These were questions that the castaways asked themselves. As for Tom, he sat at the key, clicking away, while, overhead, from the wires fastened to the dead tree, flashed out the messages.